This invention relates to wheel supporting devices for rotatably supporting wheels of passenger cars and trucks, and tapered roller bearings for supporting wheels.
A conventional wheel support device for supporting a non-driven vehicle wheel, e.g. a front wheel of a rear-wheel drive vehicle, comprises an axle (or knuckle spindle) carried by a steering knuckle, two rolling bearings mounted on the axle, and an axle hub rotatably supported by the rolling bearings and having a flange. A brake drum of a brake device and a wheel disk are mounted on the axle hub by stud bolts fixed to the flange and nuts threaded onto the stud bolts.
A back plate mounted on a flange of the steering knuckle supports a braking mechanism for applying braking force to the brake drum.
Tapered roller bearings are typically used in such wheel support devices to rotatably support the axle hub because this type of bearings are large in load capacity and high in rigidity. Tapered roller bearings are lubricated by grease sealed between the axle and the axle hub.
If grease leaks out, the tapered roller bearing may seize due to poor lubrication. If leaked grease enters the brake drum, the brake will fail, thus creating a serious safety problem. Thus, conventional wheel support devices have seal means for preventing leakage of grease, or a grease cap mounted on the outer end of the axle hub.
Such a conventional wheel support device is disclosed in Japanese utility model publication 58-85505. This device has a seal mechanism mounted between the axle and the axle hub at the inner side of a tapered roller bearing supporting the inner end of the axle hub. This needs an extra length for installation of the seal on the axle hub. This adds to the size of the entire wheel support device.
Also, since the seal mechanism uses the outer periphery of the axle as its sealing surface, it is necessary to finish the outer periphery of the axle to high accuracy. Machining of the axle is thus troublesome.
Handling of the tapered roller bearings is difficult because they are separable type roller bearings. Since a separate seal mechanism is needed besides the tapered roller bearings, assembling of the wheel support device is troublesome.
An object of this invention is to provide a wheel support device which is compact in size and easy to assemble and machine.
Another object of this invention is to provide a wheel-supporting tapered roller bearing that is easy to handle.